bone element intramembranous bone intramembranous bones ZFA:0001635 Bone that forms directly within mesenchyme, and does not replace other tissues.[TAO] Bone tissue forms directly within mesenchyme, and does not replace other tissues[TAO]. Intramembranous ossification is the formation of bone in which osteoblasts secrete a collagen-proteoglycan matrix that binds calcium salts and becomes calcified[GO]. Intramembranous ossification is the way flat bones and the shell of a turtle are formed[GO]. Unlike endochondral ossification, cartilage is not present during intramembranous ossification[WP]. UBERON:0002514 [In TAO], This term was made obsolete because it is considered a synonym of membrane bone (VSAO:0000023).[TAO] EMAPA:36615 uberon membrane bone TAO:0001644